The following relates to the illumination arts, lighting arts, solid state lighting arts, lamp and luminaire arts, illuminated flat panel arts, light engine arts, and related arts.
Backlights—the so-called edge coupled type—have historically employed a light source coupled to an edge of a light guiding plate (LGP), along which the light flux propagates by total internal reflection (TIR) with almost no losses. This enables constructing backlights with very large AR—typically of 50-100—for 10-20″ diagonal LCDs used in existing portable and desktop computers. In these types of devices a light source, usually a cold cathode fluorescent lamp, introduces light into a light guiding plate (LGP), through an edge surface thereof. The LGP is so structured that part of the light entering through the edge radiates out through the LGP's front face.
Due to its inherent compactness, ease of operation and luminance efficiency, a much more suitable type of light source for such applications (instead of fluorescent lamps) is a light-emitting diode (LED). LEDs have also been used to illuminate signs, such as an exit sign, using edge lit technology. The present disclosure is directed to using edge lit technology for a general illumination lamp. However, it can have applicability in other edge lit environments